Foamed Film Packaging

ABSTRACT

A package includes at least one layer of foamed thin film having gaseous bubbles, void volumes, or cells. The foamed thin film includes a bio-based content of between about 10% and about 100%, a caliper of between about 10 and 250 microns, and a density reduction of between about a 5% to 50%, as compared to a non-foamed thin film of substantially the same caliper that does not comprise gaseous bubbles, void volumes, or cells.

FIELD OF THE INVENTION

This application relates to the field of packages comprising a foamedfilm layer, and more specifically, to the field of packages thatcomprise a foamed film layer made at least in part of renewable,recyclable and/or biodegradable materials.

BACKGROUND OF THE INVENTION

Polyolefin-based plastic film is used to construct a wide variety ofpackages such as bags, pouches, labels and wraps that hold consumergoods. For example, bags holding stacks of disposable diapers or hygienearticles, pouches for wet wipes, and bags containing granular laundrydetergent are often made from plastic film. The plastic film that formsa package may be a single layer of film (called a monofilm), or acombination of layers that can be co-extruded, fabricated as a laminateof separately produced layers that are adhered to one another, orfabricated as an extrusion lamination whereas one layer is extruded ontoanother previously formed layer(s).

The specific compositions of the film or films that make up the packageare selected for a variety of characteristics including liquid or gaspermeability, appearance and strength. Another relevant characteristicof plastic film used for packaging is opacity. The level of opacity ofthe plastic film used in a package impacts the appearance of the packageby controlling the extent to which the package's contents are visiblethrough the package. In some circumstances, a higher opacity film may bedesirable to protect the contents from exposure to light. Additives suchas titanium oxide or other white or colored pigments are mixed with theresin for the purpose of increasing the opacity of a film. In general,decreasing the amount of resin in a film by making the film thinner willin turn reduce its opacity.

Many plastic film packages include opening features, such as, forexample, lines of weakness and/or peelable labels covering die cutopenings. These lines of weakness and/or peelable labels covering diecut openings are configured to provide convenient consumer access to thecontents of the package while maintaining the integrity of the unopenedpackage during shipment and storage. Lines of weakness, such asperforations or scores, provide a mechanism by which the consumer can,in a controlled manner, tear open a package along a predeterminedopening trajectory. The label and die cut dispensing opening combinationmay be configured to provide a re-sealable package for items thatrequire retention of moisture and/or other product ingredients withinthe package and/or items for which it is desirable to excludecontamination. The die cut defines the dispensing opening through whichitems are dispensed. The label is sized to overlap the perimeter of thedie cut dispensing opening. The label tears the die cut from the packagethe first time the label is peeled from the package. The label may becapable of completely re-covering and re-sealing the dispensing openingformed by the die cut.

Much of the cost associated with such plastic film packages is the costof the plastic resin that is used to make the film. Because the amountof plastic resin in the film is directly related to the caliper (orthickness) of the film, efforts to reduce cost in plastic film packagestypically involve using a lower caliper film that can still provide thenecessary characteristics for a particular package. Because lowercaliper film is typically weaker in terms of inherent film tearstrength, changing to a lower caliper film in packages that includes anopening feature (e.g., lines of weakness or die cut dispensing openings)requires a redesign of the opening feature to compensate for the lowertear strength of the film. For example, the cuts in a line ofperforations may be made shorter to leave more film intact between thecuts to resist unintentional tearing of the line of perforations. Scoresin the film may be made shallower to provide additional strength toresist unintentional tearing of a lower caliper film. Film connectionsbetween the cuts that define a die cut may be made longer to resistunintentional separation of the die cut from the film. The redesign ofthe opening feature is costly in terms of engineering and evaluationtime. In addition, the redesign of the opening feature typicallyrequires laborious adjustments of various manufacturing components andprocesses that create the opening feature on the film and possibly thepurchase of new tooling as well.

Recent technological developments have made it feasible to producefoamed polyolefin film of suitable thickness (from about 10 microns toabout 250 microns) and strength for the types of packages describedabove. Several exemplary foamed polyolefin films that are suitable forpackages are described in European Patent No. 1 646 677. The use offoamed thin film allows for replacement of part of the resin (e.g., fromabout 5% to about 50% by weight) with gaseous bubbles that are formed orincorporated in the film during a foaming process. Because the voids orcells left by the bubbles occupy volume that was formerly filled withresin, foamed film allows for a reduction in resin without acorresponding reduction in film caliper. One notable feature of foamedthin films is that they have a rough surface texture as compared to anon-foamed film of substantially the same caliper.

Most of the materials used in fabrication of consumer packagingapplications are derived from non-renewable resources, such aspetroleum. Often, the components of consumer packages are made frompolyolefins, such as polyethylene, polypropylene, and polyethyleneterephthalate. These polymers are derived from monomers, such asethylene, propylene, and terephalic acid, which are typically obtaineddirectly from petroleum, coal and/or natural gas via cracking andrefining processes. The price and availability of thepetroleum/coal/natural gas feedstock therefore has a significant impacton the price of consumer packages which utilize materials derived frompetroleum. As the worldwide price of petroleum escalates, so does theprice of polyolefin based packaging. Moreover, many consumers display anaversion to purchasing products that are packaged in materials derivedfrom petrochemicals. Other consumers may have adverse perceptions aboutproducts derived from petrochemicals being “unnatural” or notenvironmentally friendly.

Accordingly, it is of continued interest to provide consumer packageswhich comprise at least one polymer that is at least partially derivedfrom renewable or recycled resources, where the at least one polymer hasspecific performance characteristics making the polymer particularlyuseful in consumer packaging. It may also be desirable to providerenewable and/or recyclable packaging that is also biodegradable.

SUMMARY OF THE INVENTION

In one aspect, a package includes at least one layer of foamed thin filmhaving gaseous bubbles, void volumes, or cells. The foamed thin filmincludes a bio-based content of between about 10% and about 100%, acaliper of between about 10 and 250 microns, and a density reduction ofbetween about a 5% to 50%, as compared to a non-foamed thin film ofsubstantially the same caliper that does not comprise gaseous bubbles,void volumes, or cells.

In one aspect, a package includes at least one layer of foamed thin filmhaving gaseous bubbles, void volumes, or cells. The foamed thin filmincludes a bio-based content of between about 10% and about 100%, acaliper of between about 10 and 250 microns, a whitening additive, and adensity reduction of between about a 5% to 50%, as compared to anon-foamed thin film of substantially the same caliper that does notcomprise gaseous bubbles, void volumes, or cells. The whitening additiveis selected to produce a foamed thin film having an opacity value ofbetween about 35-99%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is cross section view of a prior art thin film that can be usedto construct thin film packages with an opening feature.

FIG. 1 b is a cross section view of a foamed thin film that can be usedto construct foamed thin film packages with an opening feature inaccordance with one or more embodiments of the present invention.

FIG. 2 a is a cross section view of a prior art thin film co-extrusionthat can be used to construct packages with an opening feature.

FIG. 2 b is a cross section view of a foamed thin film co-extrusion thatcan be used to construct packages with an opening feature in accordancewith one or more embodiments of the present invention.

FIG. 3 a is a cross section view of a prior art thin film laminate thatcan be used construct packages with an opening feature.

FIG. 3 b is a cross section view of a foamed thin film laminate that canbe used to construct packages with an opening feature in accordance withone or more embodiments of the present invention.

FIGS. 4 a and 4 b are perspective views of a package with a line ofweakness constructed in accordance with one or more embodiments of thepresent invention.

FIG. 5 is a top plan view of a package with a label and die cutdispensing opening constructed in accordance with the present invention.

FIG. 6 is an exploded fragmentary cross section view of the package ofFIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the following terms have the following meanings:

“Agricultural product” refers to a renewable resource resulting from thecultivation of land (e.g., a crop) or the husbandry of animals(including fish).

“Bio-based content” refers to the amount of carbon from a renewableresource in a material as a percent of the mass of the total organiccarbon in the material, as determined by ASTM D6866-10, Method B. Notethat any carbon from inorganic sources such as calcium carbonate is notincluded in determining the bio-based content of the material.

“Biodegradation” refers to a process of chemical dissolution ofmaterials by microorganisms or other biological means.

“Bio-identical polymer” refers to polymers that are made from monomerswhere at least one monomer is derived from renewable resources. Forinstance, a bio-identical polyolefin is made from olefins that arederived from renewable resources, whereas a petro-based polyolefin ismade from olefins typically derived from non renewable oil or gas.

“Bio-new polymer” refers to polymers that are directly derived (i.e., nointermediate compound in the derivation process) from renewableresources. Such renewable resources include cellulose (e.g. pulpfibers), starch, chitin, polypeptides, poly(lactic acid),polyhydroxyalkanoates, and the like.

“Microorganism” is defined as an organism that is too small to see withthe naked eye, such as bacteria, fungi, archaea, and protists.

“Monomeric compound” refers to an intermediate compound that may bepolymerized to yield a polymer.

“Petrochemical” refers to an organic compound derived from petroleum,natural gas, or coal.

“Petroleum” refers to crude oil and its components of paraffinic,cycloparaffinic, and aromatic hydrocarbons. Crude oil may be obtainedfrom tar sands, bitumen fields, and oil shale.

“Polymer” refers to a macromolecule comprising repeat units where themacromolecule has a molecular weight of at least 1000 Daltons. Thepolymer may be a homopolymer, copolymer, terpolymer, etc. The polymermay be produced via fee-radical, condensation, anionic, cationic,Ziegler-Natta, metallocene, or ring-opening mechanisms. The polymer maybe linear, branched and/or cross-linked.

“Polyethylene” and “polypropylene” refer to polymers prepared fromethylene and propylene, respectively. The polymer may be a homopolymer,or may contain up to about 10 mol % of repeat units from a co-monomer.

“Polymers derived directly from renewable resources” refer to polymersobtained from a renewable resource without intermediates. Typically,these types of polymers would tend be “bio-new”.

“Post-consumer recycled polymers” refer to synthetic polymers recoveredafter consumer usage and includes recycled polymers from plastic bottles(e.g., laundry, milk, and soda bottles).

“Renewable resource” refers to a natural resource that can bereplenished within a 100 year time frame. The resource may bereplenished naturally, or via agricultural techniques. Renewableresources include plants, animals, fish, bugs, insects, bacteria, fungi,and forestry products. They may be naturally occurring, hybrids, orgenetically engineered organisms. Natural resources such as crude oil,coal, and peat which take longer than 100 years to form are notconsidered to be renewable resources.

“Synthetic polymer” refers to a polymer which is produced from at leastone monomer by a chemical process. A synthetic polymer is not produceddirectly by a living organism. Synthetic polymers of the presentdisclosure can be derived from a renewable resource via an indirectroute involving one or more intermediate compounds. Typically, thesetypes of polymers would tend to be “bio-identical”, although not all ofthem are.

“Thin film” is defined as a film having a caliper that is suitable foruse in packages such as bags, pouches, labels and wraps for consumergoods, such as, for example, film calipers from about 10 to about 250microns. As used herein, the term “foamed thin film” designates a filmcontaining at least one layer having a caliper from about 10 microns toabout 250 microns and that comprises gaseous bubbles, void volumes, orcells wherein that the at least one layer exhibits a density reductionof at least about 5% by yield (as determined by ASTM D4321) versus afilm of the same thickness that does not comprise gaseous bubbles, voidvolumes, or cells.

A package and a method of constructing a package that includes at leastone layer of foamed thin film which comprise at least one polymer thatis at least partially derived from renewable or recycled resources,wherein the package includes an opening feature formed in the at leastone layer of foamed thin film, is provided herein. The foamed thin filmhas a caliper of from about 10 microns to about 250 microns thick. Thefoamed thin film comprises from about 5% to about 50% density reductionas compared to a non-foamed thin film of substantially the samecomposition and caliper.

The opening feature may include a line of weakness. Advantageously, theline of weakness may be of substantially the same configuration as aline of weakness configured for use in a non-foamed thin film ofsubstantially the same composition and caliper. The yield stress valueof the at least one layer of foamed thin film with the line of weaknessmay be at least about 90% of the yield stress value of the foamed thinfilm without the line of weakness. The opening feature may be, forexample, in the form of perforations, scores, or embossments.

Alternatively, the opening feature may include a die cut dispensingopening and a label adhered to the die cut such that the label overlapsan opening defined by the die cut. In this case, the label has adhesiveapplied to a first side whereby the label is adhered to the die cut andpeelably adhered to the foamed thin film about a periphery of theopening. Advantageously, the adhesive may be of substantially the samecomposition as adhesive configured for use on a non-foamed thin film ofsubstantially the same composition and substantially the same caliper.

The package may comprise a monolayer foamed film, or multiple layerswhere at least one layer is foamed. A package may include a foamed thinfilm co-extrusion that includes at least one foamed thin film layer. Apackage may include a foamed thin film laminate that includes at leastone foamed thin film layer. The foamed thin film layer may be, forexample, blown, cast, biaxially oriented cast, post film formationprocess oriented (i.e., stretched, drawn or tentered) in the cross ormachine orientated direction, foamed polyethylene or foamedpolypropylene.

The opening feature in the foamed thin film may be formed by weakening aselected opening trajectory or path on the foamed thin film bynon-contact means (e.g. laser, spark arcs) or mechanically via a blade,punch or pin or by weakening the selected opening trajectory with adeforming profile.

A package may include at least one layer of foamed thin film made of aplastic resin and a whitening or coloring additive that is added to theplastic resin. The resin could be a traditional petro-based polyolefin,or it could be a renewable based polyolefin, or a blend thereof.Alternatively it could be a blend comprising a petro-based or renewablebased polyolefin blend mixed with a renewable “bio-new” material that ischemically different to traditional petro-based polyolefins. The filmcould be comprised of a material or mixture of materials having a totalbio-based content of about 10% to about 100% using ASTM D6866-10, methodB.

In one embodiment, the package comprises from about 5% to about 99% byweight of a polymer (A). Polymer (A) comprises at least one or possiblymore of a low density polyethylene (LDPE), a polar copolymer ofpolyethylene such as ethylene vinyl acetate (EVA), a linear low densitypolyethylene (LLDPE), a high density polyethylene homopolymer/highdensity polyethylene copolymer, a medium density polyethylene, a verylow density polyethylene (VLDPE), a plastomer, apolypropylene/copolypropylene/heterophasic polypropylene, polyethyleneterephthalate (PET), PLA (e.g., from Natureworks), polyhydroxyalkanoate(PHA), poly(ethylene-2,5-furandicarboxylate) (PEF), cellulose (availablefrom, for example, Innovia), NYLON 11 (i.e., Rilsan® from Arkema),starch (either thermoplastic starch or starch fillers), bio-polyesters,(e.g., those made from bio-glycerol, organic acid, and anhydride, asdescribed in U.S. Patent Application No. 2008/0200591, incorporatedherein by reference), polybutylene succinate, polyglycolic acid (PGA),and polyvinyl chloride (PVC). At least one of the constituents ofpolymer (A) is at least partially derived from a renewable resource.Recycled materials may also be in added. In specific cases, materialsthat are biodegradable may be utilized. The whitening or coloringadditive is selected to produce a foamed thin film having an opacityvalue of from about 35% to about 99%. The whitening agent is ofsubstantially the same composition and is present in substantially thesame amount as would be selected to produce substantially the same lightreflectivity in a non-foamed thin film of substantially the same caliperand substantially the same composition. Some of the “bio-new” materialsmay further contribute to increasing the opacity of the film, as thepresence of this additional material within the film structure can leadto additional light reflectivity, due to their typical incompatibilitywith the polyolefin matrix. In addition to introducing renewable contentand opacity (depending on the exact blend), the addition of a “bio-new”material in particular may modify the performance of the “easy open”feature, depending on the exact type and % of “bio-new” content.

Foamed Films

FIG. 1 a is a cross section view of a thin film 100 that is used in manypackaging applications such as bags, pouches, labels and wraps that holdconsumer goods. Thin films 100 used in such packages typically have acaliper (thickness) from about 10 microns to about 250 microns and aremade of a polyolefin resin. Many different blends of components are usedin the polyolefin and components are selected for a variety ofproperties such as strength and opacity. Polyethylene (e.g., Low DensityPolyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), HighDensity Polyethylene (HDPE), Medium Density Polyethylene (MDPE),Metallocene Polyethylene (mPE), Ethyl Vinyl Acetate (EVA), cyclicpolyolefins, ionomers (Na+ or Zn+), elastomers, plastomers and mixturesthereof) and polypropylene, and blends thereof are two types ofmaterials that are often used to manufacture thin films 100. LLDPEresins could be manufactured with co-monomers that are either butane,hexene or octane. The catalysts used to produce polymers could beZiegerl-Natta based, Chromium based, metallocene, single site or othertype of catalyst. Thin films 100 can be manufactured using blown film,cast film, cast biaxially stretched film and extrusion base processes. Asecondary post film formation process could also be applied to filmssuch as Machine Direction Orientation, or other type of stretching ineither one or two directions. As can be seen in FIG. 1 a, the thin film100 is made up of a substantially solid layer of resin. The thin film100 shown in FIG. 1 a is called a monofilm because it consists of asingle layer of resin.

FIG. 2 a is a cross section view of a thin film co-extrusion 200 thatincludes a top layer 210, a core 220, and a lower layer 230. Many filmpackages use thin film co-extrusions because the composition of eachlayer may be selected to contribute a desired quality to the resultingpackage. To produce a thin film co-extrusion, resins for each layer areco-extruded while molten and cooled together to form a layered thin filmco-extrusion. As can be seen in FIG. 2 a, the thin film co-extrusion 200includes layers (e.g., the top layer 220, core layer 220, and lowerlayer 230) of each type of resin directly adjacent one another. Thinfilm co-extrusions may include layers that are selected to provide, forexample, strength, opacity, print quality, and moisture resistance. Ascan be seen in FIG. 2 a, the thin film co-extrusion 200 includes layersthat are made up of substantially solid layers of resin.

FIG. 3 a is a cross section view of thin film laminate 300 that includesa top layer 310, a top adhesive layer 315, a core 320, a bottom adhesivelayer 325, and a bottom layer 330. Thin film laminates 300 are similarto thin film co-extrusions 200 because both include layers of differentresins that are selected to contribute a desired quality to theresulting package. However, rather than being combined in a molten form,the layers of a thin film laminate 300 are separately formed and cooled.Laminates are often used when one or more of the layers is not wellsuitable for co-extrusion, such as, for example, metalized layers thatrequire significantly different processing techniques as compared toplastic layers. The separate layers (e.g., the top layer 310 the core320, and the bottom layer 330) are then fixed to one another, such as,for example, using adhesive (e.g., the top adhesive layer 315 and thebottom adhesive layer 325). As can be seen in FIG. 3 a, the thin filmlaminate 300 includes layers that are made up of substantially solidlayers of resin.

FIGS. 1 b, 2 b, and 3 b illustrate various foamed thin films 10, 20, 30that are suitable for use in packaging applications. The foamed thinfilms 10, 20, 30 each include at least one foamed layer, 12, 23, 32,respectively. As discussed above, until recently, thin films for use inpackaging were not believed to be suitable for foaming because ofconcerns about potential degradations in tear strength that could bebrought about by the loss of resin content in a foamed film. EP 1 646677 provides details about specific resin compositions and processingsteps that enable the production of foamed thin films. The resin used inmaking the foamed film may include renewable materials—either“bio-identical” or “bio-new” materials. Some non-limiting options ofapplicable bio-identical and/or bio-new materials are further detailedbelow.

Referring to FIG. 1 b, a foamed thin monofilm 10 made up of a resin 12,such as, for example, polyolefin, in which gas bubbles 14 are entrappedis shown. One way to produce foamed monofilm 10 is adding one or morechemical blowing agents such as, for example, Sodium Hydro CarbonatePowder and an acidifier to the master batch of resin 12 prior toheating. Upon heating, chemical blowing agents release carbon dioxide.The carbon dioxide expands and forms bubbles 14 in the monofilm 10during subsequent processing steps. One exemplary chemical equationdescribing the transition of the blowing agent to carbon dioxide is:

NaHCO₃(Sodium Hydro Carbonate Powder)+H⁺(Acidifier)→Na⁺+CO₂+H₂O

Some of the carbon dioxide bubbles 14 escape the molten resin 12 whileothers are trapped in the resin 12 during cooling to form voids thatremain after solidification of the resin. An alternative to the use ofchemical blowing agents that react in the resin to produce bubbles 14 isto inject a gas such as carbon dioxide or nitrogen into the moltenplastic within the extruder prior to it leaving the die, during filmmanufacture (such as practiced in the Mucell process by the TrexelCorporation). While the bubbles 14 shown in FIG. 1 b are generallyspherical in the melt and have a diameter from about 1 micron to about100 microns, other shapes are contemplated. For example, in somesolidified foamed films, the bubbles are generally cigar shaped (incross sectional analysis) and oriented in the direction of filmextrusion. In a foamed thin polyethylene monofilm having a caliper ofabout 40 microns, a typical cigar shaped bubble may be about 10 micronsin diameter (typically <20 microns) and typically from about 50 micronsto about 300 microns in length. The foam structure of a foamed thinmonofilm 10 is generally closed towards the surface such thatsubstantially all of the bubbles 14 close to the surface are closed.Because the bubbles 14 occupy volume that would have been occupied byresin 12 in a non-foamed thin film, the foamed thin monofilm 10 in FIG.1 b uses less resin 12 than its non-foamed counterpart 100 in FIG. 1 awhile maintaining substantially the same overall thickness “t.” Ofcourse, other foaming methods may be employed in the practice of thepresent invention, such as, for example, through the incorporation ofparticles (e.g. CaCO3 or PS) followed by stretching (uni-axial orbi-axial) of the film to cavitate around the particles. We alsocontemplate that bubbles with smaller dimensions could be formed with aparticular selection of materials.

FIG. 2 b shows a foamed thin film co-extrusion 20 that includes a foamedcore 23 and a non-foamed top layer 25 and a non-foamed bottom layer 27.While only the core 23 is shown as foamed, any combination of layers ina foamed thin film co-extrusion may be foamed, including the top layer25, the bottom layer 27, or the top layer 25 and the bottom layer 27, orall three layers 23, 25, 27. In addition, the core 23 need not be foamedif any other layer is foamed and any number of foamed and non-foamedlayers may be present in the foamed thin film co-extrusion. The use offoamed thin film co-extrusions 20 is well suited for many packagingapplications because layers can be selected for tensile strength,sealing properties, cost, and aesthetic impression. It has been observedthat in foamed thin film co-extrusions, foaming in one layer is limitedto the foamed layer. That is, foaming does not appear to induce foamingin adjacent non-foamed layers.

By way of example, a bag adapted for storing large granules isconstructed of a thin film laminate that includes the thin filmco-extrusion 200 (FIG. 2 a) as a base layer. This particular thin filmco-extrusion 200 is configured to present a white outer surface on whicha printed top layer (not shown) is applied while creating a blue innersurface that enhances the appearance of the white granules stored in thebag when viewing the granules through the bag's opening. The top layer210 of the thin film co-extrusion 200 is made of a white polyethylenefilm having a caliper of approximately 15 microns that is adapted forimproved interaction with the printed top layer (not shown). The core220 is made of a white polyethylene film having a caliper ofapproximately 40 microns that is adapted to mask the blue color from thebottom layer 230 from showing through. The bottom layer 230 is made of ablue polyethylene film having a caliper of approximately 15 microns thatis adapted to present a visually appealing background for the granulesin the bag.

The foamed thin film co-extrusion 20 shown in FIG. 2 b may be used toreplace the thin film co-extrusion 200. The foamed thin filmco-extrusion 20 includes a top layer 25 made of an extreme whitepolyethylene film having a caliper of approximately 15 microns, a core23 made of a foamed light white polyethylene film having a caliper ofapproximately 40 microns, and a bottom layer made of a blue polyethylenefilm having a caliper of approximately 15 microns. The foamed core 23uses about half as much resin as the non-foamed core (e.g., core 220 inFIG. 2 a). To compensate for the change in appearance caused by thepresence of bubbles in the core 23, much of the white or colored pigmentin the core 23 was removed to reduce the contrast between bubble andresin. The white intensity of the top layer was increased to achieve acomparable appearance between the thin film co-extrusion 200 and thefoamed thin film co-extrusion 20. Of course, the development of a foamedthin film co-extrusion to replace an existing thin film co-extrusion mayinvolve changing the caliper of different layers, changing the materialcomposition of different layers, and/or adding or removing layers.

FIG. 3 illustrates a foamed thin film laminate 30 that includes a foamedcore 32 and a non-foamed top layer 35 and bottom layer 39. While onlythe core 32 is shown as foamed, any combination of layers in a foamedthin film laminate may be foamed, including the top layer 35, a bottomlayer 39, both top layer 35 and bottom layer 39, or all three layers 32,35, 39. In addition, the core 32 need not be foamed if any other layeris foamed and any number of foamed and non-foamed layers may be presentin the foamed thin film laminate. The use of foamed thin film laminates30 is well suited for many packaging applications, especially forpackages that require a layer that is not readily co-extruded with otherlayers in the foamed thin film laminate. It is believed that the sametypes of adhesive (e.g., adhesives 315 and 325) used in non-foamed thinfilm laminates may be used as adhesives (e.g., adhesives 33, 37) toadhere layers in foamed thin film laminates.

Opening Features

As used herein, the term “opening feature” is defined as an aid toopening of the package that includes a weakening of a selected openingtrajectory on the foamed thin film. Two examples of such openingfeatures are linear lines of weakness and die cut dispensing openingswith labels.

FIGS. 4 a and 4 b illustrate a bag 40 that includes walls of foamed thinfilm 42 and a linear line of weakness 43. The line of weakness 43 isconfigured to remain intact until opened by the consumer along a linearopening trajectory as shown by the arrows in FIG. 4 b. The line ofweakness 43 can be formed, for example, from a line of scores thatpartially cut through the wall 42 of the bag 40 or a line ofperforations that completely cut through the wall 42 of the bag 40. Thelines of weakness 43 are of substantially the same configuration aslines of weakness that are configured for use in a bag (not shown)having non-foamed thin film walls of substantially the same caliper. Thelines of weakness can be produced using methods including scoring andperforation. The scoring or perforation may be performed using a laseror by mechanical means. The methods and method parameters used toproduce the line of weakness 43 in a foamed thin wall (e.g., wall 42)are substantially the same as methods used to produce a line of weaknessin a non-foamed thin wall of substantially the same caliper.

One method of making a line of weakness uses at least one laser. First alaser beam with sufficient wattage to evaporate a portion of the filmmaterial is focused onto the thin film. The use of laser technologyallows for very accurate control of the depth of penetration from veryslight scoring to complete perforation of the thin film. A laser usingany form of electromagnetic radiation can be used. Suitable lasers formaking lines of weakness in thin films include those based on CO₂ gas.

Another suitable method for producing the lines of weakness is the useof blades. The blades are installed on a cylinder, which is mounteddirectly on the film processing machinery so that the cuts are madeprior to formation of the bag as the film travels past theblade-equipped cylinder Different blade patterns can be used to getdifferent patterns in the line of weakness. The pressure applied to theblades is also varied during the process to control the dimensions anddepth of the cuts to ensure the bag opens easily.

Embossing is another alternative method for production of lines ofweakness. The embossing technology weakens the thin film in specificareas by means of pressure, temperature, processing time and a deformingprofile. The desired results are achieved by changing the caliper and/ormaterial structure at the embossing trajectory. The basic equipment usedfor embossing consists of a sealing jaw capable of pressing against aback plate. A deforming profile or pattern is fixed to the jaw andheated. The thin film is pressed between the deforming profile and theback plate. The main variables known to affect this process are: heatingtemperature, cooling temperature, pressure, heating time, cooling time,film tension while embossing, film tension after embossing, back platematerial, back plate thickness, back plate temperature, jaw pattern andjaw thickness. The embossing unit is typically installed after anunwinding station of the thin film and could be incorporated into thepackaging production line. EP 1 409 366 describes methods of producinglines of weakness in non-foamed thin films in detail.

Lines of weakness in foamed thin film (e.g., line of weakness 43 inFIGS. 4 a and 4 b and die cut line of weakness 52 in FIG. 5) may formmany different patterns. Those patterns may take the form of acontinuous line, a dashed line, or combinations thereof. One exemplaryline of weakness is a dashed line 43 that includes a plurality of scoredsegments 44. The length of each scored segment 44 varies from about 0.12mm to about 4.4 mm. The distance of the connections or bridges 45between adjacent scored segments 44 varies from about 0.4 mm to about 4mm. The score depth may vary depending on the thickness of the foamedthin film. Notably, any pattern that is suitable for use in a non-foamedthin film wall will also be suitable for use in a foamed thin film wallof substantially the same caliper.

Lines of weakness 43, 52 are designed to deteriorate the strength of thefoamed thin film in such a way that it can withstand normal filling,packing and handling operation and yet be easily opened by the consumer.This is achieved by reducing the trapezoidal tear strength of the foamedthin film. Reduction of the trapezoidal tear strength is also generallyaccompanied by loss of tensile strength.

The line of weakness 43, 52 may be characterized using the followingtest methods: a) ASTM D-882 Standard Test Method for Tensile Propertieson Thin Plastic Sheeting and b) ASTM D-5733 Standard Test Method forTearing Strength of Nonwoven Fabrics by the Trapezoidal Procedure. Theline of weakness 43, 52 may be characterized by three parameter valuesobtained from these standard tests. The first is yield stress value. Theyield stress value of the foamed thin film with a line of weakness asmeasured by ASTM D-882 should be no less than about 90% of the yieldstress value of the foamed thin film without a line of weakness. Second,the final or rupture stress value of the foamed thin film with the lineof weakness should be no lower than about 90% of the yield stress valueof the foamed thin film without the line of weakness. Third, the averagetrapezoidal tearing force according to ASTM D-5733 of the foamed thinfilm with the line of weakness should be less than about 4 kilograms offorce.

FIG. 5 is a top plan view of a package 48 having at least one foamedthin film wall 49. The package 48 includes a die cut dispensingopening/label combination 50 that enables a user to reseal the package48 after dispensing items from the package 48. A die cut line ofweakness 52, which can be seen through the label 54 in FIG. 5, is formedin the foamed thin film wall 49. The die cut line of weakness 52 mayhave a significantly larger proportion of weakened foamed film materialthan the line of weakness 43 in FIGS. 4 a and 4 b. The die cut line ofweakness 52 is shown having four long perforations 52 a-52 d that areattached by relatively small connections or bridges 52 e-52 h. The largeproportion of weakened foam film material in the die cut line ofweakness means that very little force will be required to completelyseparate a die cut 59 defined by the die cut line of weakness 52 fromthe foamed thin film wall 49. A label 54 covers and overlaps the die cut59. The label 54 is adhered to the foamed thin wall 49 with, forexample, adhesive (of course other methods of adhesion can be used).

To dispense an item from the package 48, the consumer peels an edge ofthe label 54 as indicated by the arrow in FIG. 5. In the first use, thelabel 54 pulls the die cut 59 free from the foamed thin wall 49 byrupturing the bridges 52 e-52 h. The die cut 59 remains adhered to anunderside of the label 54 as shown in FIG. 6. To reseal the package 48,the consumer re-adheres the label 54 to the foamed thin wall 49.

FIG. 6 is an exploded cross section view of the die cut dispensingopening/label combination 50 and the foamed thin wall 49. Adhesive 57 isshown on an underside of the label 54 with an optional adhesive-freeregion 65 at a lead edge of the label 54 that defines a tab that can begripped by a consumer. The die cut 59 defines a dispensing opening 67through which items are dispensed from the package 48. In otherembodiments (not shown), regions of different types of adhesive may bepresent on the underside of the label and the die cut dispensingopening/label combination may include intermediate layers disposedbetween the package and the label.

The perforations (or scores) 52 a-d (FIG. 5) that are used in the diecut line of weakness 52 are produced according to the same methodsdescribed above with respect to lines of weakness 43 (FIGS. 4 a, 4 b).As with the lines of weakness 43, the methods and method parameters usedto produce the die cut line of weakness 52 in a foamed thin wall (e.g.,wall 49) are substantially the same as methods used to produce a die cutdispensing opening in a non-foamed thin wall of substantially the samecaliper. In addition the adhesive that is used on the label 54 in a diecut dispensing opening/label combination (e.g., die cut dispensingopening/label combination 50) used on a foamed thin wall (e.g. thefoamed thin wall 49) is substantially the same as adhesive (e.g., theadhesive 57) that is used on a label used with a non-foamed thin wall ofsubstantially the same composition.

Polymers Derived from Renewable & Sustainable Resources

A number of renewable resources contain polymers that are suitable foruse in consumer packages (i.e., the polymer is obtained from therenewable resource without intermediates). Suitable extraction and/orpurification steps may be necessary, but no intermediate compound isrequired. Such polymers that are derived directly from renewableresources include cellulose (e.g. pulp fibers), starch, chitin,polypeptides, poly(lactic acid), polyhydroxyalkanoates, and the like. Wetypically describe such polymers as “bio-new” polymers. These polymersmay be subsequently chemically modified to improve end usecharacteristics (e.g., conversion of cellulose to yield carboxycelluloseor conversion of chitin to yield chitosan). However, in such cases, theresulting polymer is a structural analog of the starting polymer. Anypolymers derived directly from renewable resources with no intermediatecompounds (and their derivatives) that are known in the art may beuseful herein. All of these materials are within the scope of thepresent disclosure.

Synthetic polymers of the present disclosure can be derived from arenewable resource via an indirect route involving one or moreintermediate compounds. Suitable intermediate compounds derived fromrenewable resources include sugars, such as, for example,monosaccharides, disaccharides, trisaccharides, and oligosaccharides.Sugars such as sucrose, glucose, fructose and maltose may be readilyproduced from renewable resources such as sugar cane and sugar beets.Sugars may also be derived (e.g., via enzymatic cleavage) from otheragricultural products such as starch or cellulose. For example, glucosemay be prepared on a commercial scale by enzymatic hydrolysis of cornstarch. While corn is a renewable resource in North America, othercommon agricultural crops may be used as the base starch for conversioninto glucose. Wheat, buckwheat, arracaha, potato, barley, kudzu,cassava, sorghum, sweet potato, yam, arrowroot, sago, and other similarstarchy fruit, seeds, or tubers may also be used in the preparation ofglucose.

Other suitable intermediate compounds derived from renewable resourcesinclude monofunctional alcohols such as methanol or ethanol andpolyfunctional alcohols such as glycerol. Ethanol may be derived frommany of the same renewable resources as glucose. For example, cornstarchmay be enzymatically hydrolyzed to yield glucose and/or other sugars.The resultant sugars can be converted into ethanol by fermentation. Aswith glucose production, corn is an ideal renewable resource in NorthAmerica; however, other crops may be substituted. Methanol may beproduced from fermentation of biomass. Glycerol is commonly derived viahydrolysis of triglycerides present in natural fats or oils, which maybe obtained from renewable resources such as animals or plants.

Other intermediate compounds derived from renewable resources includeorganic acids (e.g., citric acid, lactic acid, alginic acid, amino acidsetc.), aldehydes (e.g., acetaldehyde), and esters (e.g., cetylpalmitate, methyl stearate, methyl oleate, etc.). Additionalintermediate compounds such as methane and carbon monoxide may also bederived from renewable resources by fermentation and/or oxidationprocesses.

Intermediate compounds derived from renewable resources may be convertedinto polymers (e.g., glycerol to polyglycerol) or they may be convertedinto other intermediate compounds in a reaction pathway which ultimatelyleads to a polymer useful in a consumer package. An intermediatecompound may be capable of producing more than one secondaryintermediate compound. Similarly, a specific intermediate compound maybe derived from a number of different precursors, depending upon thereaction pathways utilized.

Particularly desirable intermediates include olefins. Olefins such asethylene and propylene may also be derived from renewable resources. Forexample, methanol derived from fermentation of biomass may be convertedto ethylene and or propylene, which are both suitable monomericcompounds, as described in U.S. Pat. Nos. 4,296,266 and 4,083,889.Ethanol derived from fermentation of a renewable resource may beconverted into the monomeric compound ethylene via dehydration asdescribed in U.S. Pat. No. 4,423,270. Similarly, propanol or isopropanolderived from a renewable resource can be dehydrated to yield themonomeric compound of propylene as exemplified in U.S. Pat. No.5,475,183. Propanol is a major constituent of fusel oil, a by-productformed from certain amino acids when potatoes or grains are fermented toproduce ethanol.

Charcoal derived from biomass can be used to create syngas (i.e., CO+H₂)from which hydrocarbons such as ethane and propane can be prepared(Fischer-Tropsch Process). Ethane and propane can be dehydrogenated toyield the monomeric compounds of ethylene and propylene.

Other sources of materials to form polymers derived from renewable orsustainable resources include post-consumer recycled materials. Sourcesof synthetic post-consumer recycled materials can include plasticbottles (e.g., soda bottles), plastic films, plastic packagingmaterials, plastic bags and other similar materials which containsynthetic materials which can be recovered.

In one aspect, the present disclosure is directed to films having atleast one layer of a composition comprising an intimate admixture of athermoplastic polymer and a wax having a melting point greater than 25°C. The wax can have a melting point that is lower than the meltingtemperature of the thermoplastic polymer. The wax can be present in thecomposition in an amount of about 5 wt % to about 40 wt %, about 8 wt %to about 30 wt %, or about 10 wt % to about 20 wt %, based upon thetotal weight of the composition. The wax can comprise a lipid, which canbe selected from the group consisting of a monoglyceride, diglyceride,triglyceride, fatty acid, fatty alcohol, esterified fatty acid,epoxidized lipid, maleated lipid, hydrogenated lipid, alkyd resinderived from a lipid, sucrose polyester, or combinations thereof. Thewax can comprise a mineral wax, such as a linear alkane, a branchedalkane, or combinations thereof. Specific examples of mineral wax areparaffin and petrolatum. The wax can be selected from the groupconsisting of hydrogenated soy bean oil, partially hydrogenated soy beanoil, epoxidized soy bean oil, maleated soy bean oil, tristearin,tripalmitin, 1,2-dipalmitoolein, 1,3-dipalmitoolein,1-palmito-3-stearo-2-olein, 1-palmito-2-stearo-3-olein,2-palmito-1-stearo-3-olein, 1,2-dipalmitolinolein, 1,2-distearo-olein,1,3-distearo-olein, trimyristin, trilaurin, capric acid, caproic acid,caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid,and combinations thereof. The wax can be selected from the groupconsisting of: a hydrogenated plant oil, a partially hydrogenated plantoil, an epoxidized plant oil, a maleated plant oil. Specific examples ofsuch plant oils include soy bean oil, corn oil, canola oil, and palmkernel oil. The wax can be dispersed within the thermoplastic polymersuch that the wax has a droplet size of less than 10 μm, less than 5 μm,less than 1 m, or less than 500 nm within the thermoplastic polymer. Thewax can be a renewable material.

In one aspect, the present disclosure is directed to films having atleast one layer of a composition comprising an intimate admixture of athermoplastic polymer and about 5 wt % to about 40 wt % of an oil, basedupon the total weight of the composition, wherein the oil has a meltingpoint of 25° C. or less and a boiling point greater than 160° C. The oilcan comprise a lipid, which can be selected from the group consisting ofa monoglyceride, diglyceride, triglyceride, fatty acid, fatty alcohol,esterified fatty acid, epoxidized lipid, maleated lipid, hydrogenatedlipid, alkyd resin derived from a lipid, sucrose polyester, orcombinations thereof. The oil can comprise a mineral oil, such as alinear alkane, a branched alkane, or combinations thereof. The oil canbe selected from the group consisting of soy bean oil, epoxidized soybean oil, maleated soy bean oil, corn oil, cottonseed oil, canola oil,castor oil, coconut oil, coconut seed oil, corn germ oil, fish oil,linseed oil, olive oil, oiticica oil, palm kernel oil, palm oil, palmseed oil, peanut oil, rapeseed oil, safflower oil, sperm oil, sunflowerseed oil, tall oil, tung oil, whale oil, triolein, trilinolein,1-stearo-dilinolein, 1-palmito-dilinolein, lauroleic acid, linoleicacid, linolenic acid, myristoleic acid, oleic acid, palmitoleic acid,1,2-diacetopalmitin, and combinations thereof. The oil can be dispersedwithin the thermoplastic polymer such that the oil has a droplet size ofless than 10 μm, less than 5 μm, less than 1 μm, or less than 500 nmwithin the thermoplastic polymer. The oil can be a renewable material.

In one aspect, the present disclosure is directed to films having atleast one layer of a composition comprising an intimate admixture of athermoplastic starch (TPS), a thermoplastic polymer and an oil, wax, orcombination thereof present in an amount of about 5 wt % to about 40 wt%, based upon the total weight of the composition.

Some or all of the above detailed materials may also be bio-degradable.

Exemplary Synthetic Polymers

Olefins derived from renewable resources may be polymerized to yieldpolyolefins. Such polymers are typically referred to as “bio-identical”polymers. Ethylene and propylene derived from renewable resources may bepolymerized under the appropriate conditions to prepare polyethyleneand/or polypropylene having desired characteristics for use in consumerpackages. The polyethylene and/or polypropylene may be high density,medium density, low density, or linear-low density. Further,polypropylene can include homopolymer-polypropylene or co-polymerpolypropylene. Polyethylene and/or polypropylene may be produced viafree-radical polymerization techniques, or by using Ziegler-Natta (ZN)catalysis or Metallocene catalysts. Examples of such bio-sourcedpolyethylenes and polypropylenes are described in U.S. Publication Nos.2010/0069691, 2010/0069589, 2009/0326293, and 2008/0312485, PCTApplication Nos. WO2010063947 and WO2009098267; and European Patent No.1102569. Other olefins that can be derived from renewable resourcesinclude butadiene and isoprene. Examples of such olefins are describedin U.S. Publication Nos. 2010/0216958 and 2010/0036173.

Such polyolefins being derived from renewable resources can also bereacted to form various copolymers, including for example, random blockcopolymers, such as ethylene-propylene random block copolymers (e.g.,Borpact™ BC918CF manufactured by Borealis). Such copolymers and methodsof forming the same are contemplated and described for example inEuropean Patent No. 2121318. In addition, the polyolefin derived from arenewable resource may be processed according to methods known in theart into a form suitable for the end use of the polymer. The polyolefinmay comprise mixtures or blends with other polymers such as polyolefinsderived from petrochemicals.

Bio-polyethylene terephthalate is available from Teijin Fibers Ltd. Italso can be produced from the polymerization of bio-ethylene glycol withbio-terephthalic acid. Bio-ethylene glycol can be derived from renewableresources via a number of suitable routes, such as, for example, thosedescribed in WO/2009/155086 and U.S. Pat. No. 4,536,584, eachincorporated herein by reference. Bio-terephthalic acid can be derivedfrom renewable alcohols through renewable p-xylene, as described inWO/2009/079213, which is incorporated herein by reference. In someembodiments, a renewable alcohol (e.g., isobutanol) is dehydrated overan acidic catalyst in a reactor to form isobutylene. The isobutylene isrecovered and reacted under the appropriate high heat and pressureconditions in a second reactor containing a catalyst known to aromatizealiphatic hydrocarbons to form renewable p-xylene. In anotherembodiment, a renewable alcohol (e.g., isobutanol) is dehydrated anddimerized over an acid catalyst. The resulting diisobutylene isrecovered and reacted in a second reactor to form renewable p-xylene. Inyet another embodiment, a renewable alcohol (e.g., isobutanol)containing up to 15 wt. % water is dehydrated, or dehydrated andoligomerized, and the resulting oligomers are aromatized to formrenewable p-xylene. Renewable phthalic acid or phthalate esters can beproduced by oxidizing p-xylene over a transition metal catalyst (see,e.g., Ind. Eng. Chem. Res., 39:3958-3997 (2000)), optionally in thepresence of one or more alcohols.

Bio-poly(ethylene-2,5-furandicarboxylate), a.k.a., bio-PEF, can beproduced according to the route disclosed in Werpy and Petersen, “TopValue Added Chemicals from Biomass. Volume I—Results of Screening forPotential Candidates from Sugars and Synthesis Gas, produced by theStaff at Pacific Northwest National Laboratory (PNNL): NationalRenewable Energy Laboratory (NREL), Office of Biomass Program (EERE),”2004 and PCT Application No. WO 2010/077133, which are both incorporatedherein by reference.

It should be recognized that any of the aforementioned syntheticpolymers (e.g., copolymers) may be formed by using a combination ofmonomers derived from renewable resources and monomers derived fromnon-renewable (e.g., petroleum) resources. For example, the copolymercan comprise propylene repeat units derived from a renewable resourceand isobutylene repeat units derived from a petroleum source.

In addition to being formed from the synthetic polymers describedherein, the consumer packages can further include additional additives.For example, opacifying agents can be added. Such opacifying agents caninclude iron oxides, carbon black, aluminum, aluminum oxide, titaniumdioxide, talc and combinations thereof. These opacifying agents cancomprise about 0.1% to about 5% by weight of the packages; and incertain embodiments, the opacifying agents can comprise about 0.3% toabout 3% of the packages. It will be appreciated that other suitableopacifying agents may be employed and in various concentrations.Examples of opacifying agents are described in U.S. Pat. No. 6,653,523.

Furthermore, the consumer packages may comprise other additives, such asother polymers (e.g., a polypropylene, a polyethylene, a ethylene vinylacetate, a polyethylene terephthalate, a polymethylpentene, anycombination thereof, or the like—whether derived from a renewableresource or petro-based source), a filler (e.g., glass, talc, calciumcarbonate, or the like), a mold release agent, a flame retardant, anelectrically conductive agent, an anti-static agent, a pigment(inorganic or organic), an antioxidant, an impact modifier, a stabilizer(e.g., a UV absorber), wetting agents, dyes, or any combination thereof.

Some materials used in the structures described herein may be a blendcomprising a petro-based or renewable based “bio-identical” polyolefinblend mixed with a renewable “bio-new” material. Typically the “bio-new”material would be added to the petro-based or renewable based“bio-identical” polyolefin in the range 5-50 wt %, as higher than thatwould typically be difficult to process. The blend could also containsome recycled materials, typically up to around 50%—higher than thatlevel could typically cause gels to form in the film which act asimperfections.

Validation of Polymers Derived from Renewable Resources

A suitable validation technique is through ¹⁴C analysis. A small amountof the carbon dioxide in the atmosphere is radioactive. ¹⁴C carbondioxide is created when nitrogen is struck by an ultra-violet lightproduced neutron, causing the nitrogen to lose a proton and form carbonof molecular weight 14 which is immediately oxidized to carbon dioxide.This radioactive isotope represents a small but measurable fraction ofatmospheric carbon. Atmospheric carbon dioxide is cycled by green plantsto make organic molecules during photosynthesis. The cycle is completedwhen the green plants or other forms of life metabolize the organicmolecules, thereby producing carbon dioxide which is released back tothe atmosphere. Virtually all forms of life on Earth depend on thisgreen plant production of organic molecules to grow and reproduce.Therefore, the ¹⁴C that exists in the atmosphere becomes part of alllife forms, and their biological products. In contrast, fossil fuelbased carbon does not have the signature radiocarbon ratio ofatmospheric carbon dioxide.

Assessment of the renewably based carbon in a material can be performedthrough standard test methods. Using radiocarbon and isotope ratio massspectrometry analysis, the bio-based content of materials can bedetermined. ASTM International, formally known as the American Societyfor Testing and Materials, has established a standard method forassessing the bio-based content of materials. The ASTM method isdesignated ASTM D6866-10.

The application of ASTM D6866-10 to derive a “bio-based content” isbuilt on the same concepts as radiocarbon dating, but without use of theage equations. The analysis is performed by deriving a ratio of theamount of organic radiocarbon (¹⁴C) in an unknown sample to that of amodern reference standard. The ratio is reported as a percentage withthe units “pMC” (percent modern carbon).

The modern reference standard used in radiocarbon dating is a NIST(National Institute of Standards and Technology) standard with a knownradiocarbon content equivalent approximately to the year AD 1950. AD1950 was chosen since it represented a time prior to thermo-nuclearweapons testing which introduced large amounts of excess radiocarboninto the atmosphere with each explosion (termed “bomb carbon”). The AD1950 reference represents 100 pMC.

“Bomb carbon” in the atmosphere reached almost twice normal levels in1963 at the peak of testing and prior to the treaty halting the testing.Its distribution within the atmosphere has been approximated since itsappearance, showing values that are greater than 100 pMC for plants andanimals living since AD 1950. It's gradually decreased over time withtoday's value being near 107.5 pMC. This means that a fresh biomassmaterial such as corn could give a radiocarbon signature near 107.5 pMC.

Combining fossil carbon with present day carbon into a material willresult in a dilution of the present day pMC content. By presuming 107.5pMC represents present day biomass materials and 0 pMC representspetroleum derivatives, the measured pMC value for that material willreflect the proportions of the two component types. A material derived100% from present day soybeans would give a radiocarbon signature near107.5 pMC. If that material was diluted with 50% petroleum derivatives,for example, it would give a radiocarbon signature near 54 pMC (assumingthe petroleum derivatives have the same percentage of carbon as thesoybeans).

A biomass content result is derived by assigning 100% equal to 107.5 pMCand 0% equal to 0 pMC. In this regard, a sample measuring 99 pMC willgive an equivalent bio-based content value of 92%.

Assessment of the materials described herein was done in accordance withASTM D6866. The mean values encompass an absolute range of 6% (plus andminus 3% on either side of the bio-based content value) to account forvariations in end-component radiocarbon signatures. It is presumed thatall materials are present day or fossil in origin and that the desiredresult is the amount of bio-based component “present” in the material,not the amount of bio-based material “used” in the manufacturingprocess.

In one embodiment, a mono-layer film comprises a bio-based content valuefrom about 10% to about 100% using ASTM D6866-10, method B. In anotherembodiment, a mono-layer film comprises a bio-based content value fromabout 20% to about 100% using ASTM D6866-10, method B. In yet anotherembodiment, a mono-layer film comprises a bio-based content value fromabout 50% to about 100% using ASTM D6866-10, method B.

In one embodiment, a multi-layer film comprises a bio-based contentvalue from about 10% to about 100% using ASTM D6866-10, method B. Inanother embodiment, a multi-layer film comprises a bio-based contentvalue from about 20% to about 100% using ASTM D6866-10, method B. In yetanother embodiment, a multi-layer film comprises a bio-based contentvalue from about 50% to about 100% using ASTM D6866-10, method B.

In order to apply the methodology of ASTM D6866-10 to determine thebio-based content of a package, a representative sample of the componentmust be obtained for testing. In one embodiment, a representativeportion of the package can be ground into particulates less than about20 mesh using known grinding methods (e.g., Wiley® mill), and arepresentative sample of suitable mass taken from the randomly mixedparticles.

Other Materials

The consumer packages disclosed herein can optionally include a colorantmasterbatch. As used herein, a “colorant masterbatch” refers to amixture in which pigments are dispersed at high concentration in acarrier material. The colorant masterbatch is used to impart color tothe final product. In some embodiments, the carrier is a bio-basedplastic or a petroleum-based plastic, while in alternative embodiments,the carrier is a bio-based oil or a petroleum-based oil. The colorantmasterbatch can be derived wholly or partly from a petroleum resource,wholly or partly from a renewable resource, or wholly or partly from arecycled resource. Non-limiting examples of the carrier includebio-derived or oil derived polyethylene (e.g., linear low-densitypolyethylene (LLDPE), low-density polyethylene (LDPE), high-densitypolyethylene (HDPE)), bio-derived oil (e.g., olive oil, rapeseed oil,peanut oil, soybean oil, or hydrogenated plant-derived oils),petroleum-derived oil, recycled oil, bio-derived or petroleum derivedpolyethylene terephthalate, polypropylene, and a mixture thereof. Thepigment of the carrier, which can be derived from either a renewableresource or a non-renewable resource, can include, for example, aninorganic pigment, an organic pigment, a polymeric resin, or a mixturethereof. Non-limiting examples of pigments include titanium dioxide(e.g., rutile, anatase), copper phthalocyanine, antimony oxide, zincoxide, calcium carbonate, fumed silica, phthalocyamine (e.g.,phthalocyamine blue), ultramarine blue, cobalt blue, monoazo pigments,diazo pigments, acid dye, base dye, quinacridone, and a mixture thereof.In some embodiments, the colorant masterbatch can further include one ormore additives, which can either be derived from a renewable resource ora non-renewable resource. Nonlimiting examples of additives include slipagents, UV absorbers, nucleating agents, UV stabilizers, heatstabilizers, clarifying agents, fillers, brighteners, process aids,perfumes, flavors, and a mixture thereof.

In some embodiments, color can be imparted to the films of the presentinvention in any of the aspects by using direct compounding (i.e.,in-line compounding). In these embodiments, a twin screw compounder isplaced at the beginning of the injection molding, blow molding, or filmline and additives, such as pigments, are blended into the resin justbefore article formation.

Additional materials may be incorporated into the packages of thepresent invention in any of the aspects to improve the strength or otherphysical characteristics of the plastic. Such additional materialsinclude an inorganic salt, such as calcium carbonate, calcium sulfate,tales, clays (e.g., nanoclays), aluminum hydroxide, CaSiO3, glassfibers, glass spheres, crystalline silicas (e.g., quartz, novacite,crystallobite), magnesium hydroxide, mica, sodium sulfate, lithopone,magnesium carbonate, iron oxide, or a mixture thereof.

In some alternative embodiments to any of the embodiments describedherein, elements of the package, including the sealant, barriermaterial, tie layers, or mixtures thereof, include recycled material inplace of, or in addition to, the bio-based material in an amount of upto 100% of the bio-based material. As used herein, “recycled” materialsencompass post-consumer recycled (PCR) materials, post-industrialrecycled (PIR) materials, and a mixture thereof.

In some embodiments, the structure described above may incorporate abarrier layer. The barrier material is selected from the groupconsisting of aluminum, metallized polyolefin substrate, metallizedpolyethylene terephthalate substrate, metallised cellulose. PVDC, PCTFE,sol-gel coating. Instead of a metallized coating on polyolefins orpolyethylene terephthalate, the following coatings could be used—metaloxide, a nanoclay, an aluminum oxide, a silicon oxide, diamond-likecarbon (DLC), and mixtures thereof. Other barrier substrates (used withor without a coating) could include EVOH, PVOH, Nylon, PVC, liquidcrystal polymer. The substrates could include within their structure, anadditional barrier additive (not in coating form but embedded within thepolymer matrix)—one example of such additives could include nanoclays).The total barrier layer including the substrate typically has athickness of about 6 [mu]m to about 200 [mu]m. Typically the substrateunderneath the coating is cast biaxially oriented, although it could bea blown or cast film too. In some preferred embodiments, the metal isvacuum metallized aluminum. In some embodiments when the barriermaterial is a nanoclay, the nanoclay is selected from the groupconsisting of montmorillonites, vermiculite platelets, and mixturesthereof.

In embodiments of the consumer packages described herein, the ink thatis deposited can be either solvent-based or water-based. In someembodiments, the ink is high abrasive resistant. For example, the highabrasive resistant ink can include coatings cured by ultravioletradiation (UV) or electron beams (EB). In some embodiments, the ink isderived from a petroleum source. In some embodiments, the ink is derivedfrom a renewable resource, such as soy, a plant, or a mixture thereof.Non-limiting examples of inks include ECO-SURE!™ from Gans Ink & SupplyCo. and the solvent-based VUTEk® and BioVu™ inks from EFI, which arederived completely from renewable resources (e.g., corn). The ink ispresent in a thickness of about 0.5 [mu]m to about 20 [mu]m, preferablyabout 1 [mu]m to about 10 [mu]m, more preferably about 2.5 [mu]m toabout 3.5 [mu]m.

In embodiments of the consumer packages described herein, an optionallacquer functions to protect the ink layer from its physical andchemical environment, when reverse printing has not been used. In someembodiments, the lacquer is selected from the group consisting of resin,additive, and solvent/water. In some preferred embodiments, the lacqueris nitrocellulose-based lacquer. The lacquer is formulated to optimizedurability and provide a glossy or matte finish. The lacquer is presentin a thickness of up to about 25 [mu]m, preferably up to about 5 [mu]m.

Non-limiting examples of the adhesive can include acrylic, polyvinylacetate, and other commonly used adhesive tie layers suitable for polarmaterials. In some embodiments, the adhesive is a renewable adhesive,such as BioTAK® by Berkshire Labels.

In some embodiments, particular material combinations that enable thefilm structure to be biodegradable or degradable may be selected.

In some embodiments, the consumer packages described herein aresubstantially free of oxo-biodegradable additives (i.e., less than about1 wt. %, based on the total weight of the package or article) but insome embodiments oxo-biodegradable additives may be used.Oxo-biodegradable additives consist of transition metals thattheoretically foster oxidation and chain scission in plastics whenexposed to heat, air, light, or a mixture thereof. Although theshortened polymer chains theoretically can be consumed by microorganismsfound in the disposal environment and used as a food source, there is nodata to support how long these plastic fragments will persist in thesoils or marine environments, or if biodegradation of these fragmentsoccurs at all. However, in some specific material blends, such materialsmay enable faster biodegradation.

In addition embodiments where a biodegradable package is desired,certain additives may be added to tune the degradability of polymers tomeet a specific degradability. For example, numerous additives are knownto tune the degradation of polymers with or without being triggered bysome external stimulus (e.g., exposure to light) as disclosed in US2010/0222454 A1, US 2004/0010051 A1, US2009/0286060 A1 and referencestherein. Additionally, the article “Photodegradation, Photooxidation,and Photostabilization of Polymers,” by Ranby and Rabek describephotodegradant materials. While not wishing to be bound by theory, oneexample of these additives (photo acid or photobase generators) tune thelocal pH in response to exposure to certain wavelengths of light, whichresults in hydrolysis of a polyester. Once these polymers are hydrolyzedto a lower molecular weight, they are truly biodegraded bymicroorganisms.

Opacity

As discussed above, the opacity of plastic films is adjusted usingwhitening additives to achieve a desired appearance and protectionagainst light. While many methods can be used to determine the opacityof a plastic film, two exemplary test methods are described in ASTM 2805and ISO 2471. Opacity is generally expressed in terms of a percentage oflight that is absorbed by the film. For opaque LDPE thin films used inpackaging, an opacity value of from about 35% to about 99% is usuallyacceptable.

Typically, a reduction in film caliper results in a loss of opacity,which requires an increase in whitening additives such as titaniumdioxide, or other coloring additives. Thus, it would seem that thesubstitution of a foamed thin film for a non-foamed thin film wouldlikewise require an increased amount of whitening or coloring additivesto compensate for the reduction in the amount of resin that is presentin the foamed thin film. In addition, the presence of voids in thefoamed thin film would seem to further reduce the opacity of the foamedthin film as compared to a non-foamed film counterpart.

It has been discovered that the reduction in opacity of a foamed thinfilm (e.g., mono film 10 in FIG. 1 b) as compared to its non-foamed thinfilm counterpart (e.g., mono film 100 in FIG. 1 a) is not proportionalwith respect to the reduction in resin weight. In other words, theopacity of the foamed thin film (e.g., mono film 10) is only slightlylower than the opacity of the non-foamed thin film counterpart (e.g.,mono film 100) even when a significant amount of the resin has beenremoved due to foaming. The degradation in opacity is much less thanwould be expected based on the reduction in resin weight. This may bedue to light reflecting back at many angles as it encounters the curvedinner surfaces of the voids left by bubbles. As such, in many instancesit is not necessary to make any adjustments to the amount of whiteningor coloring additives used to achieve a desired opacity when using afoamed thin film in place of a non-foamed film of substantially the samecaliper and composition. However, in the case where bio-new materialsare used to make the foamed films (especially bio-new materials blendedinto a petro-based material such as polyethylene), we see yet evenhigher increase in opacity, due to the typical incompatibility with thepolyolefin matrix, which causes an increase in the reflectivity of lightimpinging on the sample.

As can be seen by the foregoing description, the use of foamed thinfilms in consumer packaging applications that include opening featuresallows for resin savings and, surprisingly, the methods of producing theopening features as well as the configuration of the opening featuresremains substantially the same as with non-foamed thin films ofsubstantially the same caliper. In addition, foamed thin films providesubstantially similar levels of opacity to their non-foamed thin filmcounterparts. These discoveries allow for a new and ready use of foamedthin films for non-foamed thin films in packages with opening featuresand/or a need for a level of opacity.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm”.

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A package comprising at least one layer of foamedthin film having gaseous bubbles, void volumes, or cells, wherein thelayer of foamed thin film comprises: i. a bio-based content of betweenabout 10% and about 100%; ii. a caliper of between about 10 and 250microns; and iii. a density reduction of between about a 5% to 50%, ascompared to a non-foamed thin film of substantially the same caliperthat does not comprise gaseous bubbles, void volumes, or cells.
 2. Thepackage of claim 1, wherein the package further comprises an openingfeature selected from the group consisting of: a line of weakness and adie cut that defines a dispensing opening, formed in the layer of foamedthin film.
 3. The package of claim 1, wherein the layer of foamed thinfilm comprises a bio-based content of between about 50% and about 100%.4. The package of claim 1, wherein the bio-based content comprisesbetween about 5% and about 96% of bio-identical materials.
 5. Thepackage of claim 1, wherein the bio-based content comprises betweenabout 5% and about 50% of bio-new materials.
 6. The package of claim 1,wherein the bio-based content is sourced from a renewable resource. 7.The package of claim 1, wherein the package comprises synthetic polymersderived from a renewable resource via an indirect route with anintermediate compound comprising sugar or vegetable starch.
 8. Thepackage of claim 1, wherein the package comprises polymers deriveddirectly from renewable resources and the polymers are selected from agroup consisting of: cellulose, starch, poly(lactic acid), andpolyhydroxyalkanoates.
 9. The package of claim 2, wherein the openingfeature comprises a line of weakness.
 10. The package of claim 1 whereinthe package comprises a foamed thin film co-extrusion that includes atleast one foamed thin film layer.
 11. The package of claim 10, whereinthe foamed thin film co-extrusion comprises a top layer, a core layer,and a lower layer, wherein the core layer is a foamed thin film layer.12. The package of claim 1, wherein the package comprises a foamed thinfilm laminate that includes at least one foamed thin film layer.
 13. Thepackage of claim 12, wherein the foamed thin film laminate comprises atop layer, a core layer, and a lower layer, wherein the core layer is afoamed thin film layer.
 14. A package comprising at least one layer offoamed thin film having gaseous bubbles, void volumes, or cells, whereinthe layer of foamed thin film comprises: i. a bio-based content ofbetween about 10% and about 100%; ii. a caliper of between about 10 and250 microns; iii. a whitening additive; and iv. a density reduction ofbetween about a 5% to 50%, as compared to a non-foamed thin film ofsubstantially the same caliper that does not comprise gaseous bubbles,void volumes, or cells; wherein the whitening additive is selected toproduce a foamed thin film having an opacity value of between about35-99%.
 15. The package of claim 14, wherein the package furthercomprises an opening feature selected from the group consisting of: aline of weakness and a die cut that defines a dispensing opening, formedin the layer of foamed thin film.
 16. The package of claim 14, whereinthe layer of foamed thin film comprises a bio-based content of betweenabout 50% and about 100/%.
 17. The package of claim 14, wherein thebio-based content comprises between about 5% and about 96% ofbio-identical materials.
 18. The package of claim 14, wherein thebio-based content comprises between about 5% and about 50% of bio-newmaterials.
 19. The package of claim 14, wherein the bio-based content issourced from a renewable resource.
 20. The package of claim 14, whereinthe package comprises synthetic polymers derived from a renewableresource via an indirect route with an intermediate compound comprisingsugar or vegetable starch.
 21. The package of claim 14, wherein thepackage comprises polymers derived directly from renewable resources andthe polymers are selected from a group consisting of: cellulose, starch,poly(lactic acid), and polyhydroxyalkanoates.
 22. The package of claim14, wherein the whitening agent comprises titanium dioxide.
 23. Thepackage of claim 15, wherein the opening feature comprises a line ofweakness.
 24. The package of claim 14, wherein the package comprises afoamed thin film co-extrusion that includes at least one foamed thinfilm layer.